1. Field of the Invention
The present invention relates to a tape cassette comprising a magnetic tape feeding reel and a winding reel in a single case.
2. Description of the Prior Art
In this type of tape cassette, a magnetic tape is passed under pressure between a head and a pad disposed abutting to the head to perform the write-in of a data on the magnetic tape or the read out of the data from the magnetic tape. A magnetic shielding plate is disposed in the rear of the pad to shield the magnetic effect to the other part of the magnetic tape which is caused by the head.
FIGS. 1 and 2 are respectively schematic views of a pad of the conventional tape cassette. In FIG. 1, the pad (4) is provided by adhering an elastic material (3) such as urethane foam on the surface of an elastic plate (2) along the direction (a) for passing the tape (1) and a magnetic sheilding plate (5) having a channel shape is set up in the rear of the pad (4). The reference numerals (6) and (7) respectively designate supporting poles for supporting the pad (4) which is projected from the inner surface of the cassette case (8).
In the conventional pad, the elastic plate (2) of the pad (4) prevents the insertion of the head (9) into the magnetic shielding plate whereby the magnetic shielding can not be obtained satisfactorily.
FIG. 2 shows the other pad proposed to improve the disadvantage of the pad of the conventional tape cassette wherein a pad (4') formed by urethane foam etc. having a rectangular cross section is directly adhered on the central portion of the surface (5'a) of the magnetic shielding plate (5'). The reference numeral (10) designates a film made of such as vinyl which is adhered at the top of the pad (4') in order to reduce the friction.
However, in the conventional tap cassette, it is necessary to elongate the pad (4') to give a good contacting effect and a buffering effect because the contacting pressure between the head (9) and the pad (4') should be compensated only by the reacting force of the urethane foam itself which forms the pad (4'). Therefore, when the tape is passed as shown in FIG. 3, the pad (4') is deformed in the direction (a) for passing the tape (1) to deflect the position of the pad (4') from the head (9) disadvantageously.
The length of the pad (4') can be substantially reduced by using resilient material having excellent elasticity for the pad (4'). However, it is difficult to improve the deformation of the pad by selecting the resilient material because a large deformation is simultaneously caused. When the deformation of the pad is large, its reaction force is also high to cause an unstable movement of the pad (4') during passing the tape. Accordingly, a level fluctuation is easily caused in the high frequency wave range to give an inferior reproducing characteristic disadvantageously.